[c-nsp] BFD feedback?

[Chris Woodfield]

BFD is a lifesaver where you have circuits such as metro ethernet  
links that don't lose link state when something in the middle blocks  
connectivity. It's less useful across WAN links that depend on end-to- 
end connectivity to maintain line protocol.

As Arie, said, the hardest part of implementation is the timer  
tuning, to get the best balance of response time vs. CPU utilization  
as well as preventing false timeouts, another side effect of setting  
the timers too low.

That said, I do feel that tying BFD to routing protocol events only  
is a bit shortsighted - why not have an option to just change line  
protocol to down in a case of BFD timeout failure, and let the  
routing protocols react the that naturally?

-C

On Oct 23, 2007, at 3:59 AM, Arie Vayner (avayner) wrote:

> The technology is very useful.
> You can get to 150ms detection time for link failures where  
> sometimes it
> takes much longer.
> On some platforms (like GSR) it also increases the scale as opposed to
> tuning down IGP timers.
>
> One thing to look for is not to be too aggressive with the timers  
> as on
> CPU based platforms it may have substantial effect.
>
> For more info:
> http://www.cisco.com/en/US/partner/products/ps6017/ 
> products_feature_guid
> e09186a00803fbe87.html
>
> Arie
>
> -----Original Message-----
> From: Vincent De Keyzer [mailto:vincent at autempspourmoi.be]
> Sent: Monday, October 22, 2007 14:44 PM
> To: Arie Vayner (avayner)
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] BFD feedback?
>
> No platform in particular, I'm just trying to understand how useful is
> this technology.
>
> V
>
> Arie Vayner (avayner) wrote:
>> Vincent,
>>
>> What kind of platforms are you looking at?
>>
>> Arie
>>
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net
>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Vincent De
>> Keyzer
>> Sent: Monday, October 22, 2007 12:29 PM
>> To: cisco-nsp at puck.nether.net
>> Subject: [c-nsp] BFD feedback?
>>
>> Hi list,
>>
>> I'm looking for feedback on BFD: is it working well (not too many
>> false alarms)? What kind of timers are you using?
>>
>> I would like to understand whether it achieves subtantially much more
>> than what you get by decreasing OSPF/BGP timers...
>>
>> Thanks
>>
>> Vincent
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